title: Tumor perfusion-related parameter of diffusion-weighted magnetic resonance imaging: correlation with histological microvessel density.
abstract: OBJECTIVE
  We obtained intravoxel incoherent motion (IVIM) parameters through biexponential analysis on diffusion-weighted MR imaging (DWI) using multiple b values. Correlation was evaluated between these parameters and histological microvessel density (MVD) for the possibility of noninvasive evaluation of MVD with DWI.
  
  
  METHODS
  Twenty-five nude mice with the HT29 colorectal cancer cells implanted were analyzed after undergoing DWI with multiple b values (0, 50, 100, 300, 500, 700, and 1000 s/mm(2)). Tissue diffusivity (D(t)), pseudo-diffusion coefficient (D(p)), and perfusion fraction (f(p)) were calculated using a biexponential analysis, and these parameters were correlated with MVD. The MVD was determined with the CD31 stain. For statistical analysis, Spearman's rank correlation was applied.
  
  
  RESULTS
  The mean value and correlation coefficient with MVD for each IVIM parameter were as follows: D(t)  = 0.98 ± 0.06 × 10(-3) mm(2)/s with r = 0.139 (P = 0.508); D(p) = 23.70 ± 7.94 × 10(-3) mm(2)/s with r = 0.782 (P < 0.001); and f(p) = 15.58 ± 5.7% with r = 0.749 (P < 0.001). D(p) and f(p) showed significant correlation with MVD, but D(t) did not.
  
  
  CONCLUSIONS
  The IVIM parameters, D(p) and f(p), on DWI might be used in the noninvasive evaluation of MVD.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University Health System, Seodaemun-gu, Seoul, Korea.
authors.forename: Hye-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Rha
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Chung
authors.forename: Hyo Sub
authors.initials: HS
authors.lastname: Shim
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Jin
authors.initials: J
authors.lastname: Hur
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Hong
authors.forename: Byoung Wook
authors.initials: BW
authors.lastname: Choi
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D019073:HT29 Cells; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D055806:Microvessels / Q000473:pathology*; D009374:Neoplasms, Experimental / Q000150:complications* / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000150:complications* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
keywords: angiogenesis; diffusion-weighted MRI; intravoxel incoherent motion; microvessel density; tumor